1. Field of the Invention
The present invention relates to a motor, and more particularly, the present invention relates to a vibration motor which is embedded into a portable phone, a beeper or the like to generate vibration as means for informing of the reception of an incoming call.
2. Description of the Related Art
In a development of a modern communication technology, personal portable communication is attracting public attention. As a representative personal portable communication device, a portable phone and a beeper can be exemplified.
In the area of personal portable communication devices, a portable phone simultaneously performs functions of a transmitter and a receiver, and a beeper only performs a function of a receiver. The portable phone and the beeper commonly have a function of informing of the reception of an incoming call.
In other words, when transmitting a message, a receiving party's portable communication device, that is, a portable phone or a beeper is informed, as an incoming call, of a condition in which a message is being inputted before the message transmitted by a portable phone or a beeper is represented by voice or characters.
A bell is most widely used as means for representing an incoming call.
While there are many kinds of bells, the bell is largely divided into a melody and a simply repeated sound.
Accordingly, a user can optionally select a kind of bell to employ in representing an incoming call, and a selected bell can be adjusted in its volume to be suited for a surrounding noise level.
However, even in the case that a volume of an incoming call is adjusted, since the incoming call still causes noise in a public place, a portable phone or a beeper can generate not only a bell, but vibration as means for informing of the reception of an incoming call.
That is to say, the incoming call can be perceived only by a user, because vibration rather than an audible bell is generated. The vibrating function can be employed by simply converting an informing mode from a bell mode to a vibrating mode.
A vibration motor is a component used as vibration generating means for informing of the reception of an incoming call by vibration.
FIG. 1 is a cross-sectional view of a conventional vibration motor.
The conventional vibration motor includes a cylindrical case 10 both ends of which are opened.
A brush base 20 which is connected via a lead wire 21 to a connector (not shown) and is formed with a through hole 22, is closely fitted into a right end of the case 10.
A housing 30 which is formed at a left end thereof with an inserting groove 31, is fastened to a left end of the case 10.
The housing 30 extends into the case 10 and is formed with a guide hole 32. The guide hole 32 is defined at a center portion of the housing 30 and is communicated with the inserting groove 31.
A commutator 40 which is selectively and electrically connected with a pair of brushes 23 of the brush base 20 to receive current therefrom, is disposed adjacent the brush base 20 inside the case 10.
The commutator 40 is provided with a contact bar 41 a right end of which is placed in the brush base 20 after passing through a space defined between ends of the pair of brushes 23 such that it is brought into contact with the ends of the pair of the brushes 23.
A shaft 50 is disposed inside the case 10. A right end of the shaft 50 is fitted into the contact bar 41 of the commutator 40 and extends to be substantially adjacent to an inner surface of the brush base 20. A left end of the shaft 50 passes through the guide hole 32 of the housing 30 and projects out of the case 10 by a predetermined length.
A magnet M is fitted around a portion of the housing 30 which extends into the case 10, and a coil C which is supplied with current from the commutator 40 is located around the magnet M such that it is radially separated by a predetermined distance from the magnet M.
The shaft 50 is rotatably supported by inside and outside oilless bearings 60 and 60' which are disposed inside and outside the case 10, respectively.
The inside oilless bearing 60 is fitted around a right end of the housing 30, and the outside oilless bearing 60' is fitted into the inserting groove 31 which is formed at the left end of the housing 30.
A weight counter 70 having a center of gravity which is eccentrically defined from a center of the shaft 50, is coupled to the left end of the shaft 50 which projects out of the case 10.
A washer W for limiting an axial movement of the shaft 50 to some extent is intervened between the weight counter 70 and a left end surface of the housing 30.
For intervening the washer W between the weight counter 70 and the housing 30, a portion of a right end surface of the weight counter 70 is depressed to a predetermined depth, as shown in FIG. 1, and the washer W is received into the depressed portion of the weight counter 70 such that it is substantially flushed with the weight counter 70.
In the vibration motor of the conventional art, constructed as mentioned above, as current is supplied from the outside through the lead wire 21, the pair of brushes 23 of the brush base 20 and the commutator 40 to the coil C, electromagnetic force is generated between the coil C and the magnet M which is fitted around the housing 30, and according to this, the shaft 50 and the weight counter 70 which are supported by the inside and outside oilless bearings 60 and 60', are rotated.
At this time, because the weight counter 70 has a center of gravity which is eccentrically defined from a center of the shaft 50, vibration is caused to be used as means for informing of the reception of an incoming call.
However, in the vibration motor of the conventional art, constructed as mentioned above, in order to place the contact bar 41 of the commutator 40 in the brush base 20, the brush base 20 must be necessarily formed with a hole which extends therethrough to communicate the outside with the inside of the case 10.
In other words, considering the fact that a distance between ends of the pair of brushes 23 of the brush base 20 is narrow and on the contrary, a diameter of the contact bar 41 is relatively large, in order to place the contact bar 41 of the commutator 40 in the brush base 20, the contact bar 41 must be inserted in a state wherein the distance between the ends of the pair of brushes 23 is widened by a jig 80 which is inserted from the outside of the brush base 20 through the through hole 22, as shown in FIG. 2.
As another example, as shown in FIG. 3, both sides of the brush base 20 are formed with a pair of through holes 22', respectively. Thereafter, a pair of jigs 80 are inserted through the pair of through holes 22', respectively, to widen the distance between the ends of the pair of brushes 23, and then, the contact bar 41 is inserted into the brush base 20.
However, in this example, when the distance between the ends of the pair of brushes 23 is widened by the pair of jigs 80, the pair of brushes 23 are likely to be deformed by the pair of jigs 80, respectively, thereby deteriorating stable contact between the pair of brushes 23 and the contact bar 41.
Also, due to the fact that a separate jig 80 is needed, as the number of components is increased, manufacturing cost is raised. Further, a process for forming the through hole 22 in the brush base 20 such that it is communicated with the inside of the case 10 and a process for widening the distance between the ends of the pair of brushes 23 must be necessarily implemented, as the number of processes is increased, assemblability is impaired.
In addition to these problems, by the presence of the washer W which is intervened between the weight counter 70 and the left end surface of the housing 30 for limiting an axial movement of the shaft 50, as the right end surface of the weight counter 70 is depressed to the predetermined depth, weight of the weight counter 70 is decreased whereby vibration capability of the weight counter 70 is lessened.